Ever since Paula Patton and Robin Thicke announced their separation in February, the “Blurred Lines” singer has begged forgiveness of his wife of eight years in every possible way. One question still remains, though: What is he so sorry for?

Rumors of cheating have dogged the 37-year-old for months, but Star can reveal that it was one ongoing affair that upset Paula so much, she could never forgive him — mainly because she had been involved with the “other woman” as well!

For about two years, the duo had been carrying on a consensual three-way relationship with a massage therapist (whom Star will refer to as “Jasmine”). Things took a disastrous turn for the worst last summer, though, when Paula caught Robin and Jasmine carrying on a separate affair behind her back.

“Paula felt betrayed and humiliated by both Robin and Jasmine,” an insider, who passed a polygraph test, reveals. “These were two people she thought she could trust the most, but in the end everything backfired on her.”

Robin’s reps have categorically denied the assertions about Jasmine, but the insider says Paula is done for good. “Paula has realized that their relationship has run its course,” the source says. “She has no plans for salvaging her marriage to Robin.”

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